(a) Field of the Invention
The present invention relates to a power factor correction circuit and a driving method thereof.
(b) Description of the Related Art
A control circuit of a typical power factor correction circuit (hereinafter, a power factor correction control circuit) receives a feedback voltage corresponding to an output voltage, and controls the output voltage according to the feedback voltage so as to keep the output voltage constant.
However, the output voltage may become an over-voltage because the control response of the power factor correction control circuit is very slow. To prevent this, the power factor correction control circuit includes an over-voltage protection function of determining that an output voltage is an over-voltage if a feedback voltage is above a predetermined voltage. At this time, a resistor element is used to divide the output voltage in order to adjust the feedback voltage within a voltage range suitable for the power factor correction control circuit. Since the resistor element is used for voltage division, a very large resistor is used to reduce power consumption caused by the resistor. At this point, if the resistance value is changed due to damage to the resistor element or the resistor element is damaged and cut off, the feedback voltage does not correspond to the output voltage, and a significant difference is generated between information about the actual output voltage and information about the output voltage delivered to the power factor correction control circuit. Moreover, a bulk capacitor connected to the output terminal of the power factor correction circuit and storing an output voltage has a fairly large capacitance. If the bulk capacitor is damaged due to over-voltage, the capacitor may explode and cause a loud noise. This is quite a large disadvantage from a user's perspective.
To avoid this, a method of preventing over-voltage by additionally connecting a resistor element to an output terminal may be used. However, this causes an increase in production costs due to increase in power consumption and expense of additional parts.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.